This invention relates to a filling head for a high speed pouch packaging machine or the like. Pouches are used for a variety of dry or liquid products such as sugar, sweeteners, salt, creamers, drink mixes, soup mixes and the like. Examples of basic pouch forming and filling machines are shown in U.S. Pat. Nos. 3,344,576, 3,453,799 and 3,667,188, the disclosures of which are incorporated herein by reference. These patents show how a continuous web of pouch material is folded, sealed on two sides, filled through the open top, sealed on top and then severed into individual, filled pouches. The severed pouches are fed to a stacker or cartoner.
Most powdered products have predictable flow characteristics such as a reasonably constant density and a consistent angle of repose. Such powders can be handled by traditional methods such as hoppers, drop tubes, belt feeders, metering blocks and the like because gravity has a known, uniform effect on the flow of these products. However, not all products are amenable to traditional handling methods. Some powders can, when agitated, readily aerate and behave more like a liquid than a powder. The most commonly found example is corn starch.
This problem has many unacceptable side effects in the packaging industry, especially for flexible pouch packaging. For example, an aerated product will occasionally flow uncontrollably through any opening, including such critical openings as the base of a funnel or gate with which it is desired to meter the product. Once in the pouch the aerated product can again behave like a liquid. For instance, as the filled pouch is drawn off the filler wheel on its way to the top sealer, tension is pulled on the web causing the pockets to collapse to the volume of the product and force the air out. Normally this is not a problem but with an aerated product, i.e., one that acts like a liquid, the product can very easily be forced out the top of the pouch along with the escaping air.